/**
* Load the cache entry for the given URI from the database.
*
* @param uri the URI of the cached resource for which to return the cache entry
* @return an instance of KiWiCacheEntry representing the caching metadata for the given resource,
* or null in case there is no entry for this resource
* @throws SQLException
*/
public KiWiCacheEntry getCacheEntry(String uri) throws SQLException {
KiWiCacheEntry cached = entryResourceCache.get(uri);
// lookup element in cache first, so we can avoid reconstructing it if it is already there
if (cached != null) {
return cached;
}
PreparedStatement query = connection.getPreparedStatement("load.entry_by_uri");
query.setString(1, uri);
query.setMaxRows(1);
// run the database query and if it yields a result, construct a new node; the method call will
// take care of
// caching the constructed node for future calls
ResultSet result = query.executeQuery();
try {
if (result.next()) {
return constructCacheEntry(result);
} else {
return null;
}
} finally {
result.close();
}
}
/**
* Remove the given cache entry from the database. The cache entry passed as argument must be a
* persistent instance of KiWiCacheEntry.
*
* @param entry
* @throws SQLException
*/
public void removeCacheEntry(CacheEntry entry) throws SQLException {
if (!(entry instanceof KiWiCacheEntry) || ((KiWiCacheEntry) entry).getId() == null) {
throw new IllegalStateException("the passed cache entry is not managed by this connection");
}
PreparedStatement deleteEntry = connection.getPreparedStatement("delete.entry");
deleteEntry.setLong(1, ((KiWiCacheEntry) entry).getId());
deleteEntry.executeUpdate();
entryIdCache.remove(((KiWiCacheEntry) entry).getId());
entryResourceCache.remove(entry.getResource().stringValue());
}
/**
* List all cache entries in the database, regardless of expiry date.
*
* @return a closeable iteration with KiWiCacheEntries; needs to be released by the caller
* @throws SQLException
*/
public CloseableIteration<KiWiCacheEntry, SQLException> listAll() throws SQLException {
PreparedStatement queryExpired = connection.getPreparedStatement("query.entries_all");
final ResultSet result = queryExpired.executeQuery();
return new ResultSetIteration<KiWiCacheEntry>(
result,
new ResultTransformerFunction<KiWiCacheEntry>() {
@Override
public KiWiCacheEntry apply(ResultSet input) throws SQLException {
return constructCacheEntry(result);
}
});
}
/**
* Remove the given cache entry from the database. The cache entry passed as argument must be a
* persistent instance of KiWiCacheEntry.
*
* @param uri URI of the entry to delete
* @throws SQLException
*/
public void removeCacheEntry(String uri) throws SQLException {
PreparedStatement deleteEntry = connection.getPreparedStatement("delete.entry_by_uri");
deleteEntry.setString(1, uri);
deleteEntry.executeUpdate();
KiWiCacheEntry cached = entryResourceCache.get(uri);
if (cached != null) {
entryResourceCache.remove(uri);
entryIdCache.remove(cached.getId());
}
}
/**
* Store the cache entry passed as argument in the database. In case the passed argument is not an
* instance of KiWiCacheEntry, it will first be converted into a KiWiCacheEntry by copying the
* fields. In this case, the stored object will not be the same instance as the object passed as
* argument.
*
* @param entry the cache entry to store
* @throws SQLException
*/
public void storeCacheEntry(CacheEntry entry) throws SQLException {
KiWiCacheEntry kEntry;
if (entry instanceof KiWiCacheEntry) {
kEntry = (KiWiCacheEntry) entry;
} else {
kEntry = new KiWiCacheEntry();
kEntry.setExpiryDate(entry.getExpiryDate());
kEntry.setLastRetrieved(entry.getLastRetrieved());
kEntry.setUpdateCount(entry.getUpdateCount());
kEntry.setResource(entry.getResource());
kEntry.setTripleCount(entry.getTripleCount());
}
if (!(entry.getResource() instanceof KiWiResource)
|| ((KiWiResource) entry.getResource()).getId() < 0) {
throw new IllegalStateException(
"the resource contained in the cache entry is not a KiWiResource!");
}
// needed before the entry can be inserted
connection.flushBatch();
kEntry.setId(connection.getNextSequence());
PreparedStatement insertEntry = connection.getPreparedStatement("store.entry");
insertEntry.setLong(1, kEntry.getId());
insertEntry.setTimestamp(2, new Timestamp(kEntry.getLastRetrieved().getTime()));
insertEntry.setTimestamp(3, new Timestamp(kEntry.getExpiryDate().getTime()));
insertEntry.setLong(4, ((KiWiNode) kEntry.getResource()).getId());
insertEntry.setInt(5, kEntry.getUpdateCount());
insertEntry.setInt(6, kEntry.getTripleCount());
insertEntry.executeUpdate();
log.debug("persisted ld-cache entry with id {}", kEntry.getId());
entryIdCache.put(kEntry.getId(), kEntry);
entryResourceCache.put(kEntry.getResource().stringValue(), kEntry);
}
